Underground » Mining Technology and Production
The aim of this project was to develop and obtain Ex d certification for a 360° panorama view flameproof enclosure incorporating both new and long established flameproof manufacturing techniques. The development of a panorama flameproof enclosure promises to provide the Australian coal industry with the necessary tool to take advantage of modern sensing instruments such as CCD video, scanning laser rangefinders and 3D spatial awareness cameras. These emerging technologies have the potential to provide new sensory tools for a variety of underground applications. For example, collision awareness and avoidance, monitoring spatial orientation for automatic and autonomous machines, identification of operators and mine staff when in proximity to moving machinery, LASC enabled longwall creep/retreat monitoring and control, monitoring movement in the roof, ribs and floor, and 'Google Earth™' style mine mapping.
Several prototype enclosures were modelled and critiqued for characteristics such as the ease of manufacture, suitability for purpose and practicality. Experiments using eye safe wide-angle class 1 scanning lasers, CCD video cameras and range imaging time of flight cameras were performed in the laboratory to determine the enclosure design suitable for each technology. Technical challenges associated with the design features of the enclosure(s) were identified along with any risk factors associated with obtaining Ex d certification.
The construction of the final prototype enclosure consists of an optically clear 180mm diameter polished polycarbonate cylinder mounted in an upright position and fitted with a mild steel base and a flameproof cover. The polycarbonate cylinder can be fitted with a clear tough protective scratch-proof and anti-static polyester film. The top of the cylindrical polycarbonate section has a threaded section by which a protective cover can be fitted. This assembly forms the complete enclosure and is achieved without external support struts or other members which would normally impede a portion of the 360° view.
In order to observe and measure any image distortion produced by the curved surface of a cylindrical body, tests were performed using different types of scanning lasers and CCD video cameras mounted inside a 150mm diameter glass cylinder. Ultimately, a class 1 scanning laser rangefinder was mounted within the enclosure and rotated through 360° in such a manner that the laser data produced a 3D point cloud image of the immediate surrounds. One major advantage of scanning laser technology is that a good quality image is produced irrespective of the lighting conditions present in the surrounding environment.
The combination of scanning laser and cylindrical flameproof enclosure will provide the coal industry with a novel 3D laser imaging sensor and this development represents a significant advancement in underground laser sensing technology. CSIRO has applied for a patent on this technology. The 360° panorama flameproof enclosure was designed to IEC 60079-0 and IEC 60079-1 (Ex d) 2014 standards and the 3D scanning laser performance has been demonstrated in an underground environment.